Vapor-liquid equilibrium data and density of the liquid phase for binary systems of carbon dioxide + methanol, hydrogen + methanol, and carbon dioxide + hydrogen at high pressures were determined. A dynamic technique with liquid-phase recirculation and on-line gas chromatography was used in this study. The equilibrium data and density were measured at temperatures between 278.15 K and 308.15 K, and pressures between 15 bar and 192.53 bar. The isothermal volume expansion behavior for the carbon dioxide + methanol system at various temperatures was also determined.

Dense gas techniques, which utilize the properties of fluids in the vicinity of the critical point, are increasingly being used for the processing of pharmaceuticals. Dense gases are unique solvents that can be used for extractions, chromatographic separations, and chemical syntheses because of their liquidlike solvation power and gaslike mass-transfer properties. The processes can be conducted at moderate temperatures and are thus suitable for many heat-labile compounds such as proteins, biocompatible polymers, and pharmaceuticals. The products formed by densegas processes are generally free of residual solvent. Recent applications of dense gas techniques have focused on micronization; crystallization of high-purity particles; sterilization; and drug formulations, including the formation of liposomes and drug coatings. The following review presents examples of drug extraction, separation, synthesis, sterilization, and particle formation and demonstrates the broad application of dense gases for drug formulation purposes in the pharmaceutical industry.

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